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Genotype differences in 13 C discrimination between atmosphere and leaf matter match differences in transpiration efficiency at leaf and whole‐plant levels in hybrid Populus deltoides × nigra
Author(s) -
RASHEED FAHAD,
DREYER ERWIN,
RICHARD BÉATRICE,
BRIGNOLAS FRANCK,
MONTPIED PIERRE,
LE THIEC DIDIER
Publication year - 2013
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02556.x
Subject(s) - transpiration , photosynthesis , stomatal conductance , water use efficiency , horticulture , respiration , botany , biology , salicaceae , chemistry , woody plant
13 C discrimination between atmosphere and bulk leaf matter (Δ 13 C lb ) is frequently used as a proxy for transpiration efficiency ( TE ). Nevertheless, its relevance is challenged due to: (1) potential deviations from the theoretical discrimination model, and (2) complex time integration and upscaling from leaf to whole plant. Six hybrid genotypes of Populus deltoides × nigra genotypes were grown in climate chambers and tested for whole‐plant TE (i.e. accumulated biomass/water transpired). Net CO 2 assimilation rates ( A ) and stomatal conductance ( g s ) were recorded in parallel to: (1) 13 C in leaf bulk material ( δ 13 C lb ) and in soluble sugars ( δ 13 C ss ) and (2) 18 O in leaf water and bulk leaf material. Genotypic means of δ 13 C lb and δ 13 C ss were tightly correlated. Discrimination between atmosphere and soluble sugars was correlated with daily intrinsic TE at leaf level (daily mean A / g s ), and with whole‐plant TE . Finally, g s was positively correlated to 18 O enrichment of bulk matter or water of leaves at individual level, but not at genotype level. We conclude that Δ 13 C lb captures efficiently the genetic variability of whole‐plant TE in poplar. Nevertheless, scaling from leaf level to whole‐plant TE requires to take into account water losses and respiration independent of photosynthesis, which remain poorly documented.